<html>
<style>
  head, body { margin: 0; padding: 0 }
  img { margin: 0 1px 1px 0 }
</style>
<body>
<!-- The right-hand image in all pairs should look the same, not change across reloads, nor
  contain any bits of the left-hand image. -->
  <img src="resources/59.jpg"><img src="resources/2-comp.jpg?11"><br>
  <img src="resources/59.jpg"><img src="resources/2-comp.jpg?21"><br>
  <img src="resources/59.jpg"><img src="resources/2-comp.jpg?31"><br>
</body>
</html>
